Add documentation for usage with `Mockk` and other mock libraries

Recently, in Mockk’s slack and KotlinTest’s slack, some users have reported troubles when using Mockk with KotlinTest, due to the mockk context not being cleared after tests.

This is due to the isolation mode being incorrect for the use case, as the user normally wants the class to be instantiated once per test (InstancePerTest isolation).

As Mockk is a very used mocking library for Kotlin, among other libraries, maybe we should create a specific part in the documentation for explaining this, or a paragraph in isolation mode.

Users don’t associate directly that the “Bug” in their mocks using KotlinTest is due to isolation mode. Usually because the default mode for JUnit is single instance per test, and we don’t do that, so writing the same test “bugs” their code because of it.

What do you think, @sksamuel ?

Also summoning @oleksiyp

[OliverCulleyDeLange]

I made a gist about getting up and running with kotest and mockk if anyone stubles upon this like i did and wants some copy paste code

[sksamuel]

It could be because MockK only scans top level fields. @kerooker is that the case ?

On Sun, 12 Apr 2020 at 10:00, Oliver Culley de Lange < [e-mail]> wrote:

Reviving this issue from the dead, as some documentation around kotest + Mockk would still be nice. I’ve just started trying out a load of test & mock frameworks for Android and kotest & mockk seem nice given their kotlin based nature. I struggled initially setting them up together. I’ll share with you my failed naive attempts so you know what a newbie might do after reading the getting started readme…

These two fail with kotlin.UninitializedPropertyAccessException: lateinit property thing has not been initialized

class FirstAttemptSpec : FreeSpec({ @MockK lateinit var thing: Thing

beforeTest {
    MockKAnnotations.init(this)
}
"Test something"{
    every { thing.name } returns "Blah"
    thing.name shouldBe "Blah"
}

})

@ExtendWith(MockKExtension::class) class SecondAttemptSpec : FreeSpec({ @MockK lateinit var thing: Thing “Test something”{ every { thing.name } returns “Blah” thing.name shouldBe “Blah” } })

On reading up on kotest styles https://github.com/kotest/kotest/blob/master/doc/reference.md#testing-styles, it was mentioned that the two style are functionally equivalent. However I tried the other style (using the init{} block) and suddenly everything worked as expected:

class WorkingSpec : FreeSpec() { @MockK lateinit var thing: Thing init { beforeTest { MockKAnnotations.init(this) } “Test something”{ every { thing.name } returns “Blah” thing.name shouldBe “Blah” } } } @ExtendWith(MockKExtension::class) class AlsoWorkingSpec : FreeSpec() { @MockK lateinit var thing: Thing

init {
    "Test something"{
        every { thing.name } returns "Blah"
        thing.name shouldBe "Blah"
    }
}

}

This is either a bug or just somethin that needs documenting for newbies like me 😃

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/kotest/kotest/issues/583#issuecomment-612629504, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAFVSGVSMLNL3UVC5NS55J3RMHJPLANCNFSM4GQEEVCA .